Vehicles commonly contain a variety of pumps, such as a water pump, fuel pump and transmission fluid pump, for providing fluid to various vehicle components and systems. Such pumps are generally mechanically driven or electrically driven. For example, the transmission fluid pump may be coupled to the transmission of the vehicle and operable to supply fluid to the transmission to power vehicle clutches as well as to provide lubrication and cooling to transmission systems. Transmission pumps such as this are generally mechanically driven with the engine of the vehicle. However, in gas/electric hybrid vehicles, the engine of the vehicle may be periodically turned off during operation of the vehicle in order to conserve fuel, such as when the vehicle is traveling at slow speeds or when the vehicle is stopped. Under such conditions, the transmission fluid pump is not powered by the engine and, instead, a separate electric pump may be used to deliver transmission fluid to the transmission system. When the engine is restarted, the transmission fluid pump driven by the engine may require several seconds to reach appropriate operating pressures and thus both the electrical pump and the mechanical pump may run simultaneously which consumes both fuel and battery power.
Further, in some situations, it may be necessary to supply transmission fluid to the transmission system when neither the electrical system nor the engine of the vehicle is running. Such situations may arise when the vehicle is being towed, such as when a passenger vehicle is being towed behind a recreational vehicle. When the vehicle is being towed in this manner the wheels of the vehicle are driving the transmission through the driveshaft(s). However, no transmission fluid is being delivered to the transmission of the vehicle as the transmission fluid pump is not powered which may result in damage to the transmission.
Accordingly, a need exists for fluid pumps with multiple alternative electrical and mechanical drive sources.